System for driving an electric pulse motor having duty cycle control of winding excitation signals

ABSTRACT

In a system for driving an electric pulse motor by changing the exciting phase in turn and stepping the rotor of the electric pulse motor, the present invention utilizes a control circuit which repeats the forward and reverse stepping signals in a ratio according to the step position, and stops or vibrates the rotor in a predetermined position between the step positions which are determined by the number of exiting phases and the number of teeth per each phase. According to the present invention, a number of steps per unit distance larger than the number of steps per unit distance which are determined by the number of exciting phases and the number of teeth per each phase can be obtained by suitably determining the sequence of input pulses of a logic circuit which determines the exciting phases. According to the exciting system of the present invention, the number of steps and the quantity of steps are not restricted by the number of phases nor by the driving system. In the driving system, by further detecting the position of the displacement of the mechanical system driven by the pulse motor and providing an error detector circuit which operates on the pulse motor via the above-mentioned control circuit so as to bring detected value into coincidence with the command value, a more precise numerical control system can be provided.

United States Patent 11 1 Kobayashi et a1.

1111 3,795,854 1 Mar. 5, 1974 Dunne 318/254 SYSTEM FOR DRIVING ANELECTRIC 3,345,547 10/1967 PULSE MOTOR HAVING DUTY CYCLE CONTROL OFWINDING EXCITATION Primary ExaminerG- Simmons SIGNALS Attorney, Agent,or FirmMaleson, Kimmelman & [75] Inventors: Kengo Kobayashi, Kawasaki;Mitsuo Ramer Manabe, Tokyo, both of Japan [73] Assignee: FujitsuLimited, Kawasaki-shi, [57] ABSTRACT ja a In a system for driving anelectric pulse motor by changing the exciting phase in turn and steppingthe [.22] Fledi 1971 rotor of the electric pulse motor, the presentinvention 21 APPL 207 037 utilizes a control circuit which repeats theforward and reverse stepping signals in a ratio according to the stepposition, and stops or vibrates the rotor in a predeter- [30] ForelgnApphcatmn Pnonty Data mined position between the step positions whichare Dec. 25, 1970 Japan 45-129759 determined by the number of exitingphases and the Feb. 10, 1971 Ja an 46-5368 number of teeth per eachphase. According to the 19, 1971 p 46-15561 present invention, a numberof steps per unit distance 30, 1971 P 46-13393 larger than the number ofsteps per unit distance Mar. 30, 1971 Japan 46-18899 which aredetermined by the number of exciting phases and the number of teeth pereach phase can be ob- [52] [1.8. CI. 318/696, 318/685 mined by suitablydetermining the sequence Of input [51] Int. Cl. 02k 37/00 pulses of alogic circuit which determines the exciting Field of Search" 318/254,685, phases. According to the exciting system of the pres- 603 entinvention, the number of steps and the quantity of steps are notrestricted by the number of phases nor 1 References Cited by the drivingsystem. In the driving system, by further UNITED STATES PATENTSdetecting the position of the displacement of the me- 3586953 6/1971Markuancnm 318/685 chanical system driven by the pulse motor and provid-3;593,097 7 1971 Gehclcin 318/696 ing an error detector Circuit whichOperates the 3579.279 5 1971 1 m 11 i 318/ 9 pulse motor via theabove-mentioned control circuit 3,466,520 9/1969 Aylikci ct al. 318/696so as to bring detected value into coincidence with the 3.66074 5/1Milek 318/696 command value, a more precise numerical control sys-3,328,658 6/1967 Thompson 318/696 tem can be provided 3,636,429 1/1972Pawlctko 318/696 3,588,661 6 1971 Newell 318/696 6 Claims, 38 DrawingFlgures CW #1 an??? CCW-] I l i I East 6 36111 ,4 2 SW Q T 61 1 a 1 l ePU L s E MODULATOR 'rmn fi.m. j I i.

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1. A system for driving a pulse motor having a plurality of excitingcoils and a rotor comprising: a. a source of command pulses havingsubstantially uniform widths, b. means being connected between said (a)source and said pulse motor for controlling the stepping of said rotor,said stepping control means including:
 1. a counter for counting saidcommand pulses, and
 2. circuit means connected to said counter whichincludes i. first means for selecting a predetermined plurality of saidexciting coils to be excited simultaneously and for supplying excitingsignals to said predetermined plurality of coils, and ii. second meansfor determining the duty cycle of each exciting signal supplied to saidselected exciting coils as a function of the count in said counter. 2.circuit means connected to said counter which includes i. first meansfor selecting a predetermined plurality of said exciting coils to beexcited simultaneously and for supplying exciting signals to saidpredetermined plurality of coils, and ii. second means for determiningthe duty cycle of each exciting signal supplied to said selectedexciting coils as a function of the count in said counter.
 2. A systemfor driving a pulse motor according to claim 1 wherein said i meansincludes: means for changing the phase of excitation so as to step therotor of said pulse motor in the forward direction or the reversedirection every time a positive pulse or negative pulse is received, andmeans for supplying the exciting signal to the exciting coils inaccordance with said phase of excitation; and wherein said second meansincludes: a pulse generator for generating a plurality of control pulseshaving a constant period and varying pulse widths, a gate circuit forselecting a pulse out of said control pulses corresponding to the countin said counter, means for generating a group of positive pulses andnegative pulses having a phase difference corresponding to the pulsewidth of said selected pulse, and means for supplying the overflowpulses of said counter and said group of positive pulses as positivepulses and the difference pulses of said counter and said group ofnegative pulses as negative pulses to said first means.
 2. circuit meansconnected to said counter which includes i. a pulse generator coupled tosaid counter for generating control pulses having a constant period andvariable pulse widths, ii. a gate circuit coupled to said pulsegenerator and said counter for selecting said predetermined plurality ofcoils to be excited simultaneously in accordance with the count in saidcounter and also for selecting a plurality of said control pulses todetermine the duty cycle of each exciting signal supplied to saidselected coils in accordance with the count in said counter, and iii.means for supplying said exciting signals to said predeterminedplurality of said exciting coils.
 3. A system of driving a pulse motoraccording to claim 1 further comprising means for controlling theswitching action of said second means on said exciting signal insynchronism with said command pulses.
 4. A system of driving a pulsemotor according to claim 1 wherein means are provided to chop saidexciting signals.
 5. A system of driving a pulse motor according toclaim 1 further comprising: detecting means for detecting thedisplacement of said rotor and producing a position signal correspondingthereto, comparing means for comparing said position signal with saidcommand pulses, compensation pulse generating means for generatingcompensation pulses in accordance with the difference between saidposition signal and said command pulses, and means for adding saidcompensation pulses to said command pulses.
 6. A system for driving apulse motor having a plurality of exciting coils and a rotor comprising:a. a source of command pulses having substantially uniform widths, b.means being connected between said (a) source and said pulse motor forcontrolling the stepping of said rotor, said stepping control meansincluding: